EE 237: Solar Energy Conversion Week 10: New Ideas BIPV Exam ...
EE 237: Solar Energy Conversion
Week 10: New Ideas BIPV Exam & Recap
June 3rd 2013 tanford University
1
TPV system
Quiz: would the efficiency be still high without the spectrally-selective mirror ? tanford University
2
TPV system
Quiz: would it work if I remove the absorber ? tanford University
3
µ-TPV system
tanford University
4
New ideas.. • • • • • • • •
Ultrathin cells Micro-concentrators Sliver Cells Spherical Cell Quantum Well / Quantum Dot cells Intermediate bandgap cells Multiple Exciton Generation Hot carrier cell
tanford University
5
Third generation PV
tanford University
6
Quantum Well / Dot Cell Light
Light
large Eg
small Eg
large Eg
small Eg
large Eg
vs.
Quiz: Is this better than having one bandgap ?
tanford University
EE 237 : Aneesh Nainani
7
Examples of Bandgap Engineering: Double Heterostructures and Quantum Wells
tanford University
8
Quantum Dot Cells
• Need to ensure that current boost is greater than reduction in voltage. • Cyrium Technologies tanford University
EE 237 : Aneesh Nainani
9
Intermediate Bandgap Cells
tanford University
EE 237 : Aneesh Nainani
10
Intermediate Bandgap Cells
tanford University
EE 237 : Aneesh Nainani
11
How to make intermediate bandgap
tanford University
EE 237 : Aneesh Nainani
12
Multiple Exciton Generation (MEG)
tanford University
EE 237 : Aneesh Nainani
13
MEG efficiency limits
tanford University
EE 237 : Aneesh Nainani
14
How does MEG work ?
tanford University
EE 237 : Aneesh Nainani
15
MEG is an unlikely process
tanford University
EE 237 : Aneesh Nainani
16
MEG using QD
tanford University
EE 237 : Aneesh Nainani
17
MEG: experimental evidence
tanford University
EE 237 : Aneesh Nainani
18
MEG: experimental evidence
tanford University
EE 237 : Aneesh Nainani
19
Photon Up conversion and down conversion Up
+
Down
=
+
Quiz: one example each of Up / Down conversion ? tanford University
EE 237 : Aneesh Nainani
20
Energy conversion
tanford University
21
BIPV
tanford University
22
BIPV @ Stanford http://sustainablestanford.stanford.edu/buildings
tanford University
23
BIPV – Y2E2 – Roof
tanford University
24
BIPV – Y2E2 – Windows
• Different windows on N, S, E, W • “Light shelf” on the S facing side tanford University
25
BIPV – Y2E2 – Basement (S)
tanford University
26
BIPV – Y2E2 – Atrium
tanford University
27
BIPV – Y2E2 – Atrium
Fire retarding cover
Computer controlled louvers
tanford University
28
BIPV – Y2E2 – Misc Polygal windows
Active chilling
tanford University
29
Recap and Exam
tanford University
30
Final Exam • June 7th (Friday) • 4:15 pm @ wallenberg hall • Practise problems on class website on Tue • There is a lot of material we have covered over the quarter, I recommend revising it for the exam. Hopefully you will see commonalities and connections between these wide variety of topics tanford University
31
Week 1 • Motivation - Overview - Real cost of solar (energy payback time) • Basic physics of solar energy conversion - Nature of sunlight - Basic operation of a solar cell and loss mechanisms - Schockley-Queisser Limit and tandem cells
tanford University
EE 237 : Aneesh Nainani
32
EE237: Bird Eye View
• Mirrors much cheaper than solar cell • Cell efficiency increases with concentration Q: What's the limitation of this approach ?
tanford University
EE 237 : Aneesh Nainani
33
Week 2 • Light trapping, light concentration and tracking - Etendue conservation, limits to concentration, types of concentrators - Tiedje/Yablonovitch limits to light trapping and current/future approaches
tanford University
EE 237 : Aneesh Nainani
34
EE237: Bird Eye View
Q: Most of the solar cell available in the market today, look very different from what you can buy in the market, why ?
tanford University
EE 237 : Aneesh Nainani
35
Week 3-5 • Crystalline PV Technologies (lectures 5-9) - Silicon feedstock - Process Technology - Basic design of a c-Si solar cell - Factors that limit efficiency - Surface passivation - c-Si device designs - Multi junction III-V solar cells
tanford University
EE 237 : Aneesh Nainani
36
EE237: Bird Eye View
~ 1/3rd of the cost coming from cost of silicon wafer tanford University
EE 237 : Aneesh Nainani
37
Week 6-7 1
α-Si
• Thin-Film PV Technologies - Single junction a-Si: carrier collection vs. light absorption. LID. - a-Si tandems and triple junction cells - CdTe and CIGS solar cells - New approaches: organic PV, nanostructured PV, etc.
tanford University
EE 237 : Aneesh Nainani
2 CdTe
3 CIGS
4 OPV
38
EE237: Bird Eye View η ~ 23 %
η ~ 20 %
Q: What is the efficiency of the module ? tanford University
EE 237 : Aneesh Nainani
39
Week 8
• PV Systems - From cell to module (materials, efficiency losses) - Installations: sizing, effects of mismatch - Effect of shading and soiling - Inverters, microinverters and DC/DC conversion
Central inverter tanford University
Micro-inverter
EE 237 : Aneesh Nainani
40
Q: What is this ? How does it compare to PV ? tanford University
EE 237 : Aneesh Nainani
41
Week 9
• Solar Thermal and ThermoPhotovoltaics - Principles of solar thermal energy conversion - Parabolic through, power tower and dish - Thermophotovoltaics
tanford University
EE 237 : Aneesh Nainani
42
Week 10
• Theoretical Limits and New Ideas - Ultimate solar conversion efficiency - Intermediate gap cells, micro concentrators, impact ionization, etc.
tanford University
EE 237 : Aneesh Nainani
43
Opportunities Materials Scientists
New materials for thin film solar cells Growth of III-V MJ cells
Electrical Engineers
Make better solar cells Make better inverters Make it easier to plug solar into the grid
Optics
Improve light trapping
Mechanical Engineers
Make better manufacturing equipment Enable use of thinner wafers Automate module assembly
Chemical Engineers
Bring down costs of the purified materials needed for PV
Geologists
Find more indium, tellurium and silver
tanford University
44
Even more opportunities Design
Make installation easier
Architects
Incorporate solar into buildings
Finance
Figure out how to help people manage the up front costs (e.g. Solar City)
Marketing
Help people see that they can save money and help the environment
Computer Science Control theorists
Make the grid smarter so that it can handle more power from an intermittent source
Electrochemists
Improve batteries and electrolyzers
tanford University
45
Feedback • Please fill out the course evaluation online. Constructive feedback really helps make the course better. • Please take time to thank Raisul and Erica for all they did for smooth running of the course
tanford University
46
Week 10: New Ideas BIPV Exam & Recap
June 3rd 2013 tanford University
1
TPV system
Quiz: would the efficiency be still high without the spectrally-selective mirror ? tanford University
2
TPV system
Quiz: would it work if I remove the absorber ? tanford University
3
µ-TPV system
tanford University
4
New ideas.. • • • • • • • •
Ultrathin cells Micro-concentrators Sliver Cells Spherical Cell Quantum Well / Quantum Dot cells Intermediate bandgap cells Multiple Exciton Generation Hot carrier cell
tanford University
5
Third generation PV
tanford University
6
Quantum Well / Dot Cell Light
Light
large Eg
small Eg
large Eg
small Eg
large Eg
vs.
Quiz: Is this better than having one bandgap ?
tanford University
EE 237 : Aneesh Nainani
7
Examples of Bandgap Engineering: Double Heterostructures and Quantum Wells
tanford University
8
Quantum Dot Cells
• Need to ensure that current boost is greater than reduction in voltage. • Cyrium Technologies tanford University
EE 237 : Aneesh Nainani
9
Intermediate Bandgap Cells
tanford University
EE 237 : Aneesh Nainani
10
Intermediate Bandgap Cells
tanford University
EE 237 : Aneesh Nainani
11
How to make intermediate bandgap
tanford University
EE 237 : Aneesh Nainani
12
Multiple Exciton Generation (MEG)
tanford University
EE 237 : Aneesh Nainani
13
MEG efficiency limits
tanford University
EE 237 : Aneesh Nainani
14
How does MEG work ?
tanford University
EE 237 : Aneesh Nainani
15
MEG is an unlikely process
tanford University
EE 237 : Aneesh Nainani
16
MEG using QD
tanford University
EE 237 : Aneesh Nainani
17
MEG: experimental evidence
tanford University
EE 237 : Aneesh Nainani
18
MEG: experimental evidence
tanford University
EE 237 : Aneesh Nainani
19
Photon Up conversion and down conversion Up
+
Down
=
+
Quiz: one example each of Up / Down conversion ? tanford University
EE 237 : Aneesh Nainani
20
Energy conversion
tanford University
21
BIPV
tanford University
22
BIPV @ Stanford http://sustainablestanford.stanford.edu/buildings
tanford University
23
BIPV – Y2E2 – Roof
tanford University
24
BIPV – Y2E2 – Windows
• Different windows on N, S, E, W • “Light shelf” on the S facing side tanford University
25
BIPV – Y2E2 – Basement (S)
tanford University
26
BIPV – Y2E2 – Atrium
tanford University
27
BIPV – Y2E2 – Atrium
Fire retarding cover
Computer controlled louvers
tanford University
28
BIPV – Y2E2 – Misc Polygal windows
Active chilling
tanford University
29
Recap and Exam
tanford University
30
Final Exam • June 7th (Friday) • 4:15 pm @ wallenberg hall • Practise problems on class website on Tue • There is a lot of material we have covered over the quarter, I recommend revising it for the exam. Hopefully you will see commonalities and connections between these wide variety of topics tanford University
31
Week 1 • Motivation - Overview - Real cost of solar (energy payback time) • Basic physics of solar energy conversion - Nature of sunlight - Basic operation of a solar cell and loss mechanisms - Schockley-Queisser Limit and tandem cells
tanford University
EE 237 : Aneesh Nainani
32
EE237: Bird Eye View
• Mirrors much cheaper than solar cell • Cell efficiency increases with concentration Q: What's the limitation of this approach ?
tanford University
EE 237 : Aneesh Nainani
33
Week 2 • Light trapping, light concentration and tracking - Etendue conservation, limits to concentration, types of concentrators - Tiedje/Yablonovitch limits to light trapping and current/future approaches
tanford University
EE 237 : Aneesh Nainani
34
EE237: Bird Eye View
Q: Most of the solar cell available in the market today, look very different from what you can buy in the market, why ?
tanford University
EE 237 : Aneesh Nainani
35
Week 3-5 • Crystalline PV Technologies (lectures 5-9) - Silicon feedstock - Process Technology - Basic design of a c-Si solar cell - Factors that limit efficiency - Surface passivation - c-Si device designs - Multi junction III-V solar cells
tanford University
EE 237 : Aneesh Nainani
36
EE237: Bird Eye View
~ 1/3rd of the cost coming from cost of silicon wafer tanford University
EE 237 : Aneesh Nainani
37
Week 6-7 1
α-Si
• Thin-Film PV Technologies - Single junction a-Si: carrier collection vs. light absorption. LID. - a-Si tandems and triple junction cells - CdTe and CIGS solar cells - New approaches: organic PV, nanostructured PV, etc.
tanford University
EE 237 : Aneesh Nainani
2 CdTe
3 CIGS
4 OPV
38
EE237: Bird Eye View η ~ 23 %
η ~ 20 %
Q: What is the efficiency of the module ? tanford University
EE 237 : Aneesh Nainani
39
Week 8
• PV Systems - From cell to module (materials, efficiency losses) - Installations: sizing, effects of mismatch - Effect of shading and soiling - Inverters, microinverters and DC/DC conversion
Central inverter tanford University
Micro-inverter
EE 237 : Aneesh Nainani
40
Q: What is this ? How does it compare to PV ? tanford University
EE 237 : Aneesh Nainani
41
Week 9
• Solar Thermal and ThermoPhotovoltaics - Principles of solar thermal energy conversion - Parabolic through, power tower and dish - Thermophotovoltaics
tanford University
EE 237 : Aneesh Nainani
42
Week 10
• Theoretical Limits and New Ideas - Ultimate solar conversion efficiency - Intermediate gap cells, micro concentrators, impact ionization, etc.
tanford University
EE 237 : Aneesh Nainani
43
Opportunities Materials Scientists
New materials for thin film solar cells Growth of III-V MJ cells
Electrical Engineers
Make better solar cells Make better inverters Make it easier to plug solar into the grid
Optics
Improve light trapping
Mechanical Engineers
Make better manufacturing equipment Enable use of thinner wafers Automate module assembly
Chemical Engineers
Bring down costs of the purified materials needed for PV
Geologists
Find more indium, tellurium and silver
tanford University
44
Even more opportunities Design
Make installation easier
Architects
Incorporate solar into buildings
Finance
Figure out how to help people manage the up front costs (e.g. Solar City)
Marketing
Help people see that they can save money and help the environment
Computer Science Control theorists
Make the grid smarter so that it can handle more power from an intermittent source
Electrochemists
Improve batteries and electrolyzers
tanford University
45
Feedback • Please fill out the course evaluation online. Constructive feedback really helps make the course better. • Please take time to thank Raisul and Erica for all they did for smooth running of the course
tanford University
46
